An organic EL device has a multilayer structure comprising (i) a light emitting layer comprising a luminescent material and (ii) a hole transport layer and an electron transport layer, which sandwich the luminescent layer, and (iii) an anode and a cathode, which sandwich the hole transport layer, the luminescent layer and the electron transport layer.
The organic EL device utilizes light emission (fluorescence or phosphorescence) occurring at deactivation of an exciton formed by the recombination of electron and hole, which are injected in the luminescent layer. The organic EL device is widely used for a display and other applications.
The cyclic azine compound according to the present invention includes both of a 1,3,5-triazine compound and a pyrimidine compound. The 1,3,5-triazine compound is novel and characterized as having a nitrogen-containing condensed ring aromatic group which is bonded, directly or via a phenylene group, to a phenyl group bonded on 2-position of a triazine ring. The pyrimidine compound also is novel and characterized as having a nitrogen-containing condensed ring aromatic group which is bonded, directly or via a phenylene group, to a phenyl group bonded on 2-position of a pyrimidine ring.
Examples of an organic EL device comprising a 1,3,5-triazine compound as a constituent are disclosed in patent document 1. This 1,3,5-triazine compound does not have a nitrogen-containing condensed ring aromatic group, and therefore, this compound is distinguished from the 1,3,5-triazine compound of the present invention.
1,3,5-triazine derivatives are disclosed in patent document 2. These 1,3,5-triazine derivatives include those which have a 1,3,5-triazine ring and a nitrogen-containing aromatic group. However, no working examples are given wherein specific examples of such 1,3,5-triazine derivatives are described.
As an example of a 1,3,5-triazine compound which is useful as a constituent of an organic EL device, a triazine compound having two phenanthrolinyl groups is known (see, for example, patent document 3) and a triazine compound having two isoquinolinyl groups is known (see, for example, patent document 4). These triazine compounds have a structure such that two nitrogen-containing condensed ring aromatic groups are symmetrically arranged via an arylene group on a phenyl group bonded to 2-position of the triazine ring, and therefore, this compound is distinguished from the 1,3,5-triazine compound of the present invention.